Defect-engineered Pd/WO3−x nanostructures with tunable morphology for enhanced visible-NIR light-driven catalysis

Abstract

Semiconductor-based heterogeneous photocatalysis has garnered significant attention, showing considerable promise as a strategy for addressing problems associated with renewable energy and environmental remediation. Plasmonic semiconductors enhance photocatalysis by enabling localized surface plasmon resonance that enhances the light absorption and generates hot carriers. These carriers drive redox reactions efficiently, improving the photocatalytic performance. Herein, Pd nanoparticles (NPs) (2.5 wt%) were successfully deposited onto a non-stoichiometric form of tungsten trioxide (WO_3−x) with oxygen defects using a controlled morphology technique. Generating oxygen-deficient states in the WO₃ structure significantly enhanced its electronic properties, facilitating improved charge carrier separation and superior catalytic performance. The prepared catalysts were characterized using various techniques, including UV-vis spectroscopy, EPR, FT-EXAFS, HR-TEM, Mott–Schottky, XPS, and N₂ physisorption analysis. The light-driven catalytic performance of the prepared nanocatalyst was evaluated through the conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), utilizing hydrogen generated in situ from ammonia borane (AB). A superior reaction rate of 0.75 min⁻¹ was obtained for Pd colloids/WO_3−x catalyst, a 2.5 times enhancement in comparison to the reaction performed in dark conditions. The study demonstrates a crucial role of Pd NPs supported on WO_3−x and morphology-controlled photocatalytic activity. Based on scavenger experiments, a plausible reaction mechanism is suggested to explain the enhanced charge separation and photocatalytic performance. Our findings underscore the potential of WO_3−x-based materials with plasmonic properties in photocatalytic application reactions.